Identifying reproductions of images is often desirable. Examples include copies made by a photocopier of successive time frame photographs in locations such as airplane cockpits. Other examples are sequential photographs used by police or aerial photographs used in mapping. In the prior art, successive reproduced images were difficult to arrange in sequence where there was little or no change between successive reproduced images, such as in aerial photography. One method of identifying the sequence of photographs or reproduced images was the use of a clock built into the camera and reproduced on a portion, usually a corner, of the photograph by means of prisms within the camera. One disadvantage of this method is that where a long period of time elapses between photographs, the timing mechanism may have reached its maximum count or value and restarted from the beginning. Thus, a photograph produced shortly after a stop watch has made a complete revolution might be mistakenly assumed to have been taken prior to one which was taken when the stop watch had made half a revolution.
Document security makes it desirable to have numbered copies of reproduced reports and the like. Numbering each page of each copy is time consuming and may result in errors where there are large numbers of copies being made.
The invention disclosed herein is a document identifying device useful in many image reproducing situations.